Power of 9’s
Goal: Get to the number 9 with the numbers you're given.
Definition:
9’s compliment is 0 because it’s already 9.
8’s compliment is 1 because 8+1=9.
7’s compliment is 2 because 7+2=9.
6's compliment is 3 because 6+3=9.
5's compliment is 4 because 5+4=9.
etc.
Supposed you want to do this subtraction by only adding:
872 - 218 = ???
Take the higher number and get its 9’s compliment:
872 turns into 127 (8+1=9, 7+2=9, 2+7=9)
Take that number and add it to the second number in our equation:
127 + 218 = 345
Which gives you 345, now get its 9’s compliment and you have your answer:
345 turns into 654 (3+6=9, 4+5=9, 5+4=9)
In other words, 872 – 218 = 654 but I used only addition to find it!
Now you can add all your subtractions to get the answer! Silly party trick, but it shows the power of 9 and the glorious complexity of God's system.
By the way, anything multiplied by 9 sums to a product of 9.
9 x 2 = 18 (1+8=9)
145 x 99 = 14,355 (1+4+3+5+5=18 or 1+8=9)